From 343153754c59d0eba86622c3a562dea4c0e66594 Mon Sep 17 00:00:00 2001
From: Georgios Andrianakis <geoand@gmail.com>
Date: Thu, 5 Jan 2023 13:34:21 +0200
Subject: [PATCH] Ensure that Kotlin implementation of QuarkusApplication works
 properly

Fixes: #30190

Follows up on: #30058 (which incorrectly checked for QuarkusApplication
as a superclass)

(cherry picked from commit d5fb7fcacb724e51c66d45b3725468324a970d56)
---
 .../deployment/steps/MainClassBuildStep.java  | 20 +++++--------------
 .../src/main/kotlin/org/acme/Main.kt          | 15 ++++++++++++++
 2 files changed, 20 insertions(+), 15 deletions(-)
 create mode 100644 integration-tests/gradle/src/main/resources/kotlin-grpc-project/src/main/kotlin/org/acme/Main.kt

diff --git a/core/deployment/src/main/java/io/quarkus/deployment/steps/MainClassBuildStep.java b/core/deployment/src/main/java/io/quarkus/deployment/steps/MainClassBuildStep.java
index 5238f2e607e2f..947e55779c7b5 100644
--- a/core/deployment/src/main/java/io/quarkus/deployment/steps/MainClassBuildStep.java
+++ b/core/deployment/src/main/java/io/quarkus/deployment/steps/MainClassBuildStep.java
@@ -418,25 +418,15 @@ public MainClassBuildItem mainClassBuildStep(BuildProducer<GeneratedClassBuildIt
     }
 
     private static String sanitizeMainClassName(ClassInfo mainClass, IndexView index) {
-        String className = mainClass.name().toString();
+        DotName mainClassDotName = mainClass.name();
+        String className = mainClassDotName.toString();
         if (isKotlinClass(mainClass)) {
             MethodInfo mainMethod = mainClass.method("main",
                     ArrayType.create(Type.create(DotName.createSimple(String.class.getName()), Type.Kind.CLASS), 1));
             if (mainMethod == null) {
-                ClassInfo classToCheck = mainClass;
-                boolean hasQuarkusApplicationSuperClass = false;
-                while (classToCheck != null) {
-                    DotName superName = classToCheck.superName();
-                    if (superName.equals(QUARKUS_APPLICATION)) {
-                        hasQuarkusApplicationSuperClass = true;
-                        break;
-                    }
-                    if (superName.equals(OBJECT)) {
-                        break;
-                    }
-                    classToCheck = index.getClassByName(superName);
-                }
-                if (!hasQuarkusApplicationSuperClass) {
+                boolean hasQuarkusApplicationInterface = index.getAllKnownImplementors(QUARKUS_APPLICATION).stream().map(
+                        ClassInfo::name).anyMatch(d -> d.equals(mainClassDotName));
+                if (!hasQuarkusApplicationInterface) {
                     className += "Kt";
                 }
             }
diff --git a/integration-tests/gradle/src/main/resources/kotlin-grpc-project/src/main/kotlin/org/acme/Main.kt b/integration-tests/gradle/src/main/resources/kotlin-grpc-project/src/main/kotlin/org/acme/Main.kt
new file mode 100644
index 0000000000000..46b8d7e400e0d
--- /dev/null
+++ b/integration-tests/gradle/src/main/resources/kotlin-grpc-project/src/main/kotlin/org/acme/Main.kt
@@ -0,0 +1,15 @@
+package org.acme
+
+import io.quarkus.runtime.Quarkus
+import io.quarkus.runtime.QuarkusApplication
+import io.quarkus.runtime.annotations.QuarkusMain
+
+@QuarkusMain
+class Main : QuarkusApplication {
+
+    @Throws(Exception::class)
+    override fun run(vararg args: String?): Int {
+        Quarkus.waitForExit()
+        return 0
+    }
+}